(1) Field of the Invention
The present invention relates to a solid-state imaging device and a camera, and in particular to a technique of color separation by using a color filter of a solid-state imaging device that detects visible light and near-infrared light.
(2) Description of the Related Art
In recent years, the range of application for solid-state imaging devices such as digital cameras and mobile phones has been expanding rapidly, and colorization has become essential in any field.
FIGS. 8A and 8B are diagrams related to a solid-state imaging device according a conventional art. FIG. 8A illustrates an array of pixels of the solid-state imaging device according the conventional art. FIG. 8B illustrates the spectral characteristics of the pixels of the solid-state imaging device according the conventional art.
As shown in FIGS. 8A and 8B, an infrared cut filter is removed, and an infrared light filter (IR filter) that allows transmission of only the IR components of incident light is deposited on pixels in addition to color filters that allow transmission of RGB light components. A solid-state imaging device with such a structure having infrared-light-receiving pixels that detect only the IR components has been devised (Patent Reference 1: Japanese Unexamined Patent Application Publication No. 2006-237737, for example).
In the solid-state imaging device of Patent Reference 1: Japanese Unexamined Patent Application Publication No. 2006-237737, a signal generated by the infrared-light-receiving pixels (hereinafter referred to as IR pixels) serves as a reference signal that provides each light-receiving pixel with information regarding an amount of signals generated due to the IR components. That is, using reference signals from the IR pixels allows color signal processing to eliminate effects of the IR components included in each color signal generated by each RGB light-receiving pixel.
Here, a color filter of each IR pixel is formed by laminating an R filter and a B filter.
It is to be noted that the above structure shown in FIGS. 8A and 8B is a structure of a solid-state imaging device using an organic material, such as pigments and dyes, as a color filter (hereinafter referred to as an organic filter). A structure of a solid-state imaging device using a dielectric multilayer film as a color filter has also been devised (for example, Patent Reference 2: see pamphlet of International Application Publication No. 05/069376).
FIGS. 9A and 9B are diagrams related to a solid-state imaging device according a conventional art. FIG. 9A illustrates a cross-sectional structure of a color filter of a solid-state imaging device according to Patent Reference 2 in the case of using a dielectric multilayer film as a color filter. FIG. 9B illustrates the transmission characteristics of the color filter of the solid-state imaging device disclosed Patent Reference 2: see pamphlet of International Application Publication No. 05/069376.
The color filter using a dielectric multilayer film according to the solid-state imaging device disclosed in Patent Reference 2: see pamphlet of International Application Publication No. 05/069376, separates colors of R, G, B, and IR as with the above mentioned organic filter. Although Patent Reference 2 does not mention the spectral characteristics of the IR filter, it can be achieved by changing the thickness of a spacer layer.